/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.wss4j.policy.model;

import org.w3c.dom.Attr;
import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;

import java.io.PrintWriter;
import java.io.StringWriter;
import java.io.Writer;

/**
 * This class is a utility to serialize a DOM node as XML. This class
 * uses the <code>DOM Level 2</code> APIs.
 * The main difference between this class and DOMWriter is that this class
 * generates and prints out namespace declarations.
 */
final class DOM2Writer {
    public static final char NL = '\n';
    public static final String LS = System.getProperty("line.separator",
            Character.valueOf(NL).toString());

    public static final String XMLNS_NS = "http://www.w3.org/2000/xmlns/";
    public static final String XML_NS = "http://www.w3.org/XML/1998/namespace";

    private DOM2Writer() {
        // Complete
    }

    /**
     * Return a string containing this node serialized as XML.
     */
    public static String nodeToString(Node node) {
        StringWriter sw = new StringWriter();
        serializeAsXML(node, sw, true);
        return sw.toString();
    }

    /**
     * Return a string containing this node serialized as XML.
     */
    public static String nodeToString(Node node, boolean omitXMLDecl) {
        StringWriter sw = new StringWriter();
        serializeAsXML(node, sw, omitXMLDecl);
        return sw.toString();
    }

    /**
     * Serialize this node into the writer as XML.
     */
    public static void serializeAsXML(Node node, Writer writer,
                                      boolean omitXMLDecl) {
        serializeAsXML(node, writer, omitXMLDecl, false);
    }

    /**
     * Serialize this node into the writer as XML.
     */
    public static void serializeAsXML(Node node, Writer writer,
                                      boolean omitXMLDecl,
                                      boolean pretty) {
        PrintWriter out = new PrintWriter(writer);
        if (!omitXMLDecl) {
            out.print("<?xml version=\"1.0\" encoding=UTF-8 ?>");
        }
        NSStack namespaceStack = new NSStack();
        print(node, namespaceStack, out, pretty, 0);
        out.flush();
    }

    private static void print(Node node, NSStack namespaceStack,
                              PrintWriter out, boolean pretty,
                              int indent) {
        if (node == null) {
            return;
        }
        boolean hasChildren = false;
        int type = node.getNodeType();
        switch (type) {
            case Node.DOCUMENT_NODE:
                Node child = node.getFirstChild();
                while (child != null) {
                    print(child, namespaceStack, out, pretty, indent);
                    child = child.getNextSibling();
                }
                break;
            case Node.ELEMENT_NODE:
                namespaceStack.push();
                if (pretty) {
                    for (int i = 0; i < indent; i++) {
                        out.print(' ');
                    }
                }
                out.print('<' + node.getNodeName());
                String elPrefix = node.getPrefix();
                String elNamespaceURI = node.getNamespaceURI();
                if (elPrefix != null && elNamespaceURI != null && elPrefix.length() > 0) {
                    boolean prefixIsDeclared = false;
                    try {
                        String namespaceURI = namespaceStack.getNamespaceURI(elPrefix);
                        if (elNamespaceURI.equals(namespaceURI)) {
                            prefixIsDeclared = true;
                        }
                    } catch (IllegalArgumentException e) { //NOPMD
                        //
                    }
                    if (!prefixIsDeclared) {
                        printNamespaceDecl(node, namespaceStack, out);
                    }
                }
                NamedNodeMap attrs = node.getAttributes();
                int len = (attrs != null) ? attrs.getLength() : 0;
                for (int i = 0; i < len; i++) {
                    Attr attr = (Attr) attrs.item(i);
                    out.print(' ' + attr.getNodeName() + "=\"");
                    normalize(attr.getValue(), out);
                    out.print('\"');
                    String attrPrefix = attr.getPrefix();
                    String attrNamespaceURI = attr.getNamespaceURI();
                    if (attrPrefix != null && attrNamespaceURI != null) {
                        boolean prefixIsDeclared = false;
                        try {
                            String namespaceURI = namespaceStack.getNamespaceURI(attrPrefix);
                            if (attrNamespaceURI.equals(namespaceURI)) {
                                prefixIsDeclared = true;
                            }
                        } catch (IllegalArgumentException e) { //NOPMD
                            //
                        }
                        if (!prefixIsDeclared) {
                            printNamespaceDecl(attr, namespaceStack, out);
                        }
                    }
                }
                child = node.getFirstChild();
                if (child != null) {
                    hasChildren = true;
                    out.print('>');
                    if (pretty) {
                        out.print(LS);
                    }
                    while (child != null) {
                        print(child, namespaceStack, out, pretty, indent + 1);
                        child = child.getNextSibling();
                    }
                } else {
                    hasChildren = false;
                    out.print("/>");
                    if (pretty) {
                        out.print(LS);
                    }
                }
                namespaceStack.pop();
                break;
            case Node.ENTITY_REFERENCE_NODE:
                out.print('&');
                out.print(node.getNodeName());
                out.print(';');
                break;
            case Node.CDATA_SECTION_NODE:
                out.print("<![CDATA[");
                out.print(node.getNodeValue());
                out.print("]]>");
                break;
            case Node.TEXT_NODE:
                normalize(node.getNodeValue(), out);
                break;
            case Node.COMMENT_NODE:
                out.print("<!--");
                out.print(node.getNodeValue());
                out.print("-->");
                if (pretty) {
                    out.print(LS);
                }
                break;
            case Node.PROCESSING_INSTRUCTION_NODE:
                out.print("<?");
                out.print(node.getNodeName());
                String data = node.getNodeValue();
                if (data != null && data.length() > 0) {
                    out.print(' ');
                    out.print(data);
                }
                out.println("?>");
                if (pretty) {
                    out.print(LS);
                }
                break;
        }
        if (type == Node.ELEMENT_NODE && hasChildren) {
            if (pretty) {
                for (int i = 0; i < indent; i++) {
                    out.print(' ');
                }
            }
            out.print("</");
            out.print(node.getNodeName());
            out.print('>');
            if (pretty) {
                out.print(LS);
            }
            hasChildren = false;
        }
    }

    private static void printNamespaceDecl(Node node,
                                           NSStack namespaceStack,
                                           PrintWriter out) {
        switch (node.getNodeType()) {   //NOPMD
            case Node.ATTRIBUTE_NODE:
                printNamespaceDecl(((Attr) node).getOwnerElement(), node,
                                   namespaceStack, out);
                break;
            case Node.ELEMENT_NODE:
                printNamespaceDecl((Element) node, node, namespaceStack, out);
                break;
        }
    }

    private static void printNamespaceDecl(Element owner, Node node,
                                           NSStack namespaceStack,
                                           PrintWriter out) {
        String namespaceURI = node.getNamespaceURI();
        String prefix = node.getPrefix();
        if (!(namespaceURI.equals(XMLNS_NS) && "xmlns".equals(prefix))
            && !(namespaceURI.equals(XML_NS) && "xml".equals(prefix))) {
            if (getNamespace(prefix, owner) == null) {
                out.print(" xmlns:" + prefix + "=\"" + namespaceURI + '\"');
            }
        } else {
            prefix = node.getLocalName();
            namespaceURI = node.getNodeValue();
        }
        namespaceStack.add(namespaceURI, prefix);
    }

    /**
     * Normalizes and prints the given string.
     */
    public static void normalize(String s, PrintWriter fOut) {
        int len = (s != null) ? s.length() : 0;
        for (int i = 0; i < len; i++) {
            char c = s.charAt(i);
            switch (c) {
                case '<':
                    fOut.print("&lt;");
                    break;
                case '>':
                    fOut.print("&gt;");
                    break;
                case '&':
                    fOut.print("&amp;");
                    break;
                case '"':
                    fOut.print("&quot;");
                    break;
                default:
                    fOut.print(c);
                    break;
            }
        }
    }

    private static String getNamespace(String prefix, Node e) {
        while (e != null && e.getNodeType() == Node.ELEMENT_NODE) {
            Attr attr = null;
            if (prefix == null) {
                attr = ((Element) e).getAttributeNode("xmlns");
            } else {
                attr = ((Element) e).getAttributeNodeNS(XMLNS_NS, prefix);
            }
            if (attr != null) {
                return attr.getValue();
            }
            e = e.getParentNode();
        }
        return null;
    }
}
